Ron Adams, president of the Mulch and Soil Council, dishes the dirt on how growers can get the best results from their growing media.

Q. What are the most common mistakes growers make when choosing and handling growing media?

A. Ignoring the relationship between price and quality. It appears that shopping for price is the biggest mistake. Basic components for most growing mixes are very similar, and the cost difference between producers should not be substantial. If growers are buying products below the general market price, they must ask what shortcuts were taken to allow the producer to deliver products significantly below market value. The first place to look is the quality, composition and source of materials in the product.

Not verifying the materials they receive. Too often I have helped growers who received soilless mix that was produced with components that are not tested before planting.

Not trialing a large enough sample to fully evaluate a new media. A growing mix trial should be more than a few pots mixed in with a regular crop. A proper trial should contain a sufficient number of containers that will be treated on their own merit for watering and feeding.

Not maintaining moisture. Not adding adequate moisture to the mix before planting can be a problem. Adding additional moisture before planting assures that the mix will take moisture thoroughly at the initial watering. Initially there needs to be about a 70-percent moisture level in the medium before planting. This allows for more uniform moisture after planting, which allows greater plant uniformity.

Moisture at shipping is usually 50 percent or less. Additional moisture at shipping increases the cost of the mix since the producer would be shipping water. It is best to add additional moisture the day before using the product to allow moisture to be wicked uniformly throughout the soil particles. Adding additional water at planting allows for wet and dry spots in the medium on the initial watering.

Q. Do growers have a tendency to blame growing media as one of the first causes for production problems?

A. I do not believe growers always blame the media first, but come to that conclusion after trying to correct crop deficiencies. Diagnosing plant problems is difficult under any circumstances.

While experience with other crops and media should be useful in quickly narrowing possible problem sources, testing and reviewing the information is the only proper way to solve a problem. There are many factors, including the media, to evaluate when plants are not growing as expected.

Q. What percentages of growers test growing media before planting?

A. Less than 10 percent. If growers are buying their media from a reputable source, they feel they should have been tested prior to arrival. In most cases it has gone through some quality-control checks. That does not mean that it has undergone a complete analysis.

Q. What percentage of growers test during the production cycle?

A. I would estimate that only about 20 percent of the growers test during a production cycle as a routine with a complete laboratory analysis. Another 20 percent test for pH and electrical conductivity (EC) during production.

That means an estimated 60 percent of growers do not do any soil testing during production unless they have a problem. These are the businesses that gamble with the future of their production crop by being reactive, not proactive.

Q. How often during a production cycle should growers test their soil?

A. I would like to see soil tests done two to four weeks after planting the crop. During that testing period growers have a chance for their water and fertility program to impact the soil solution.

Some growers track weekly the pH and EC of the soil solution during the production cycle. They make a graphical record of the results to evaluate the changes. This allows them to see the effects of water and fertilizer over time.

Regular measurements allow time to take corrective measures to keep a crop from getting off track. Again, timing depends on the crop. A plug grower might have to test sooner. For long-term crops, such as poinsettias, growers should test about every four weeks.

Q. Do growers need to use a commercial laboratory for soil tests, or can growers could do a satisfactory job if they have the right testing equipment and have been trained on how to use it?

A. Soil-testing equipment is too technical for most growers. It requires calibration and constant use to maintain accuracy. I definitely feel commercial laboratories are necessary. A grower should establish a relationship with a laboratory so he can understand how to interpret the results.

Growers should be able to use a reliable pH and EC meter that can reflect changes during production. However, pH and EC readings will not adequately reflect all the nutrient balances of the soil solution.

Q. Are most growers satisfied using the same growing media from crop to crop?

A. Most growers would like to have one growing mix that works for everything. Unfortunately, different seasons and crops require adaptations to basic growing mixes. Geraniums and pentas have a high soil solution pH requirement (6.3-6.5), while pansies prefer a lower pH (5.5-5.8).

I remember when every grower was told to use a mix of 1 soil:1 peat moss:1 perlite, which would work for everything. The limitation of a 1-1-1 mix was native soils vary from region to region and have become very difficult to obtain. Native soils also require steam sterilization, and fewer growers are using a boiler that generates steam for greenhouse heating.

Q. Why do growers switch growing mixes?

A. It is often a relationship issue as opposed to price or even performance of the mix itself. Price is always a consideration, but service and reliability are more often the reason for change.

There are many reliable companies with qualified staff that can assist growers with their soil needs. Growers should have a relationship with their suppler.

Q. Do you think peat moss and bark will continue to be the two major components of most commercial mixes? Are there any byproducts that have the potential to become a major component of commercial mixes?

A. I have spent over 30 years looking for a substitute for Canadian sphagnum peat moss and have not found anything that can replace it on an economical basis. Our bark resources are a byproduct of the lumber industry and are very compatible with Canadian sphagnum peat and other media amendments.

You can grow in just about anything if you want to take the time to understand all of the variables. I have customers who produce cut snapdragons in straight perlite. I wouldn't recommend it for the typical grower.

A grower's job is to produce plants, not experiment with various soil amendments. Let the manufacturers and the institutional researchers look for new amendments that are economical to use, bearing in mind that it has to be reproducible as well as economical.

Some people thought coir would replace Canadian sphagnum peat; Ideally it is compatible with Canadian sphagnum peat since it does not provide an acid buffer in the soil as well as Canadian sphagnum peat. The biggest challenge to manufacturers is to maximize media component resources to provide economical soilless mixes that growers can afford.

Q. During the late 1990s there was a flurry of activity among some states to require growing media manufacturers to register their products and provide ingredient components on the product labels. Has that activity died down?

A. The activity has died down. The industry through the Mulch and Soil Council developed model legislation through Association of American Plant Food Control Officials Inc. (www.aapfco.org) that would provide uniform legislation. Since AAPFCO has adopted the model legislation, only New Hampshire has adopted the model law.

It seems as though once the industry became involved, individual states lost interest. Manufacturers have conformed and provide a statement of ingredients on their labels.

The industry has worked together to satisfy governmental requirements in a manner that is fair and equitable. If states feel compliance already exists with what they would require, there is no incentive to engage in the long process of adopting legislation for an issue that essentially isn't a problem any more.

Q. Describe the Mulch and Soil Council's National Product Certification Program.

A. The Certification Program can be found on the council's Web site, www.mulchandsoilcouncil.org. It provides manufacturers a way to certify that retail consumer products such as potting soil have met minimum requirements for either a standard potting soil or a premium potting soil. The industry answers the question as to how to distinguish between premium and standard potting soil.

This is a voluntary program that is specific to mulch and potting soil products, soil amendments and mulches and does not presently include commercial products. It is designed to give the public as well buyers a way to differentiate potting soil that has met a certain level of standards. Not every manufacturer has chosen to register products and it is open to both council members and non-members.

Q. Do the members of the Mulch and Soil Council police each other?

A. Mulch and Soil Council is a voluntary organization. It offers suggestions for best business practices, but it is not a policing organization unless a company is certifying potting soil through its program. MSC provides industry education through its annual meeting, and is available to assist members with questions.

MSC has been very successful in tackling industry issues such as training plant managers on best business practices as well as labeling products. It has also provided industry input when states are adopting legislation which has resulted in the model law on horticultural substrates approved through AAPFCO.

MSC has provided industry information to producers about the hazards of construction and demolition debris used in mulch, as well as the herbicide clorpyralid found in yard waste, adopted standards for potting soils, soil conditioners and mulches.

Q. If the manufacturer doesn't appear to be trying to resolve a problem, can the council step in?

A. Only in the case of certification does the Mulch and Soil Council have any ability to rectify product-quality issues. I would assume there would be a greater economic risk to the manufacturer in not correcting a problem than any influence the council could bear on the producer.

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© 2003 Branch-Smith Publishing